He describes Aiki in terms very similar to yours. For example, on pages 30-31 he writes:

"(After doing sumo exercises for 14 years)... I realised I wasn't training my muscles, but rather something inside my body...something very near the core of the body that was not the physical body was being strengthened by the exercise....these are conscious techniques...not muscular power or Ki. However, since the conscious world is non-material, it usually has no influence over the physical world. Aiki is like a key to combine them."